Interosseous and hypothenar muscles have been removed to a depth of 5 mm. on the proximal section to illustrate the interosseous and hypothenar fasciae and the various septa which extend to the metacarpal bones. The flexor tendons to the middle finger (15) have also been removed from the proximal section to display the synovial sheath which encloses them. The "mid-palmar space", a cleft-like region of delicate connective tissue deep to the flexor tendons and lumbrical muscles, has been spread open at 14. A single, dense, fibrous septum (2) extends from the palmar aponeurosis to the volar interosseous fascia lateral to the second lumbrical. This separates the flexor tendons and lumbrical of the index finger from the remaining tendons and lumbricals. The "mid-palmar space" is thus interrupted by this septum. A similar space, or cleft, lateral to this septum has been designated as the "thenar space". This cleft can be traced around the distal margin of the adductor pollicis to the area between the adductor and the first dorsal interosseous muscle. Other septa similar to the one described (2) appear more distally in the palm. These separate the remaining tendons and lumbricals from each other as they approach the fingers.